1. Field of the Invention
The present invention relates to a tool replacing device to be mounted to an industrial robot device, and more specifically, to a hollow shaped (cylindrical) tool replacing device equipped with shock censors.
2. Description of the Related Art
In an industrial robot device for use in welding/cutting, operations such as welding and cutting are performed, with various tools such as a welding torch and a cutting tool mounted to a tool holder located at the tip portion of a robot arm.
Welding/cutting operation by the industrial robot device, however, involves a problem of causing a failure of the welding torch or of imposing load on the robot device because a tool make contact with, or collide against an object to be operated.
Furthermore, for example, as disclosed in Japanese Unexamined Patent Application Publication No. 5-192890, the contact/collision of the tool not only cause damage to the welding torch, but also raises a problem that the tool which has been mounted to the tool holder upon being positioned in a mounting position relative to the tool holder deviates from the mounting position.
The deviation of the mounting position of the tool does not allow an accurate operation to be performed, resulting in a troublesomeness of interrupting the operation to again perform positioning for mounting. Moreover, regarding mounting work, because the tool is fixed to the tool holder with bolts or the like, the mounting/demounting of the tool cannot be easily performed.
Regarding the above-described contact/collision problem of the tool, there has been known arrangements for achieving an improvement by detecting the contact/collision of the tool usually by mounting a shock sensor(s) at the tip portion of the robot arm.
Furthermore, in order to prevent deviation of the mounting position of the tool due to contact or collision, Japanese Unexamined Patent Application Publication No. 9-330125 discloses a tool holder that accommodates/corrects an error in position or inclination even if the tool makes contact with an object to be operated, by providing a plurality of springs to the tool holder to which the welding torch or the like is connected.
On the other hand, in order to facilitate mounting/demounting of the tool, Japanese Unexamined Patent Application Publication No. 2003-117868 discloses a holder employing a pressurized air for the mounting of the tool.
Meanwhile, the tool such as a welding torch or the like mounted to the robot arm is high in weight, and therefore, in order to accurately move the welding torch or the like up to a position to be moved, it is desirable that the welding torch or the like be arranged on an axial line in the longitudinal direction of the robot arm.
However, according to the above-described Japanese Unexamined Patent Application Publication No. 9-330125, because the above-described holder has therein springs for accommodating errors in position and inclination, the tool cannot be held by being inserting into the holder, that is, the tool cannot be accommodated within the robot arm and hence it must be held outside the robot arm.
As a result, the tool cannot be arranged on the axial line in the longitudinal direction of the robot arm, which raises the issue of impairing the accuracy of the robot arm's operation of moving the tool such as the welding torch.
Moreover, the above-described problem that the mounting/demounting is troublesome because the tool is fixed by screws or bolts, has not yet been settled.
According to the Japanese Unexamined Patent Application Publication No. 2003-117868, the tool is held by engaging a ball (refer to a “ball 47” in FIG. 1) with a tool plate (refer to a “tool plate 30” in FIG. 1) by pressurization using air, and therefore, if power supply is interrupted by an electric outage or the like, supply of the pressurized air is stopped, so that the tool plate and the ball is disengaged and the welding torch or the like ends up falling off the tool holder.
Also, according to the Japanese Unexamined Patent Application Publication No. 2003-117868, even though a fail-safe mechanism is provided as a countermeasure against the falling-off of the welding torch or the like from the tool holder, if pressurization by air is stopped, the ball and the tool plate do not engage with each other, which cannot solve the problem that the welding torch or the like deviates from the tool holder's mounting position that has been positioned.
Meanwhile, among conventional hollow-shaped holders, there has been no holder equipped with a shock sensor.